The victims included Galveston Island Beach Patrol Chief Peter Davis, who was stung about 15 times during his morning workout, the newspaper reported. As a result, lifeguards are now flying blue flags at their towers to alert swimmers to the jellyfish, known locally as sea nettle.

“We have a very scientific method for establishing when we have a blue flag,” Davis told The Galveston County Daily News. “We all do a workout in the morning before our shift. If a whole lot of us get stung, it’s a blue flag day.”

The sting of a sea nettle generally lasts about 20 minutes, he said.

“It’s not like a (Portuguese) man-of-war where you’re going to be hurting a couple of hours, and it’s not quite like a cabbage head where you just barely feel it.”

The treatment involves spritzing the area of the sting with a saline solution, Davis told the newspaper.